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BMI Calculator

Calculate your Body Mass Index instantly. Enter your weight and height to see your BMI and health category.

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Read: BMI vs Body Fat Percentage: What's the Difference? ->

BMI is a screening tool, not a diagnostic measure. Consult a healthcare professional for medical advice.

What is BMI Calculator?

Body Mass Index (BMI) is a number calculated from your weight and height that provides a quick snapshot of whether your body weight falls within a healthy range. It is widely used by clinicians and researchers as a low-cost screening tool to flag potential weight-related health risks. However, BMI has real limitations: it cannot distinguish between muscle mass and fat mass, so a muscular athlete may be classified as "overweight" despite having very low body fat. BMI also does not account for where fat is distributed on the body — abdominal fat carries different health risks than fat stored elsewhere. Researchers note that BMI thresholds developed from European populations may not apply equally across all ethnic groups. For a fuller picture of body composition, consider waist circumference, waist-to-hip ratio, or a DEXA scan alongside your BMI.

How to use

  1. Select your preferred unit system — Metric (kg, cm) or Imperial (lbs, ft/in).
  2. Enter your current weight and height in the fields provided.
  3. Click Calculate to instantly see your BMI score.
  4. Review your BMI category (Underweight, Normal, Overweight, or Obese) on the color-coded gauge.
  5. Read the on-screen guidance to understand what your result means for your health.
  6. Consult a healthcare professional if your BMI falls outside the Normal range or if you have concerns about body composition.

Why it matters

Maintaining a healthy BMI reduces the risk of type 2 diabetes, cardiovascular disease, hypertension, sleep apnea, and several cancers. Even modest weight loss of 5–10% of body weight in people who are overweight can meaningfully lower blood pressure, improve insulin sensitivity, and reduce joint strain. Tracking BMI over time gives you an objective reference point for monitoring the effect of lifestyle changes — independent of how you feel day to day.

Pro tip

If you lift weights or do resistance training regularly, your BMI may overestimate your body fat. Pair your BMI result with a waist circumference measurement (aim for under 94 cm / 37 in for men, under 80 cm / 31.5 in for women) for a more accurate health picture.

Frequently Asked Questions

Body Mass Index (BMI) is a measure of body fat based on height and weight. It is calculated by dividing weight in kilograms by the square of height in meters. BMI is used as a screening tool to indicate whether a person may have a weight problem.
For most adults, a BMI of 18.5–24.9 is considered healthy. A BMI below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese. However, BMI is a screening tool and does not directly measure body fat.
BMI is a useful screening tool but has limitations. It does not distinguish between muscle and fat, and may not be accurate for athletes, elderly people, or during pregnancy. Use it as a general indicator, not a medical diagnosis.
BMI = weight (kg) ÷ height² (m²). For example: 70 kg ÷ (1.75 m)² = 70 ÷ 3.0625 = 22.9. In imperial units: BMI = (weight in lbs × 703) ÷ height² (in²).